Mechanical game machines of the type in which a player spins reels provided with indicia on their perimeter to display a random combination of indicia when the reels stop are well known. They are basically of two kinds: in the purely mechanical type, an analog mechanical timing device with a randomly variable delay stops the reels in random positions; in the electronic type, random numbers are electronically generated by an algorithm using seed numbers, and are translated into an appropriate visual display, usually on a cathode-ray tube screen.
For psychological reasons, probably relating to the feeling of impersonality conveyed by an electronic device as opposed to a mechanical one, electronic game devices of this type have had little success, although the use of devices having an electronically generated randomness is preferable. Electronic devices are not only cheaper to build and maintain, but in a typical mechanical device, the motive power for the timing mechanism is a spring which is cocked by the player. Depending on how fast or how slowly the spring is cocked, the kinetic energy released by it can vary slightly, thus giving the player a small amount of control over the timing mechanism. This factor, as well as the effect of mechanical wear, can make it possible for the odds of any given indicia combination being displayed to vary by as much as several percentage points from the theoretical odds dictated by the distribution of the indicia on the reels.